From a4abd7a80addb4a9547f7dfc7812566b60ec505c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>
Date: Wed, 6 Dec 2017 20:21:24 +0100
Subject: [PATCH] usbnet: fix alignment for frames with no ethernet header
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

The qmi_wwan minidriver support a 'raw-ip' mode where frames are
received without any ethernet header. This causes alignment issues
because the skbs allocated by usbnet are "IP aligned".

Fix by allowing minidrivers to disable the additional alignment
offset. This is implemented using a per-device flag, since the same
minidriver also supports 'ethernet' mode.

Fixes: 32f7adf633b9 ("net: qmi_wwan: support "raw IP" mode")
Reported-and-tested-by: Jay Foster <jay@systech.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/usb/qmi_wwan.c | 2 ++
 drivers/net/usb/usbnet.c   | 5 ++++-
 include/linux/usb/usbnet.h | 1 +
 3 files changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -70,9 +70,11 @@ static void qmi_wwan_netdev_setup(struct
 		net->hard_header_len = 0;
 		net->addr_len        = 0;
 		net->flags           = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
+		set_bit(EVENT_NO_IP_ALIGN, &dev->flags);
 		netdev_dbg(net, "mode: raw IP\n");
 	} else if (!net->header_ops) { /* don't bother if already set */
 		ether_setup(net);
+		clear_bit(EVENT_NO_IP_ALIGN, &dev->flags);
 		netdev_dbg(net, "mode: Ethernet\n");
 	}
 
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -482,7 +482,10 @@ static int rx_submit (struct usbnet *dev
 		return -ENOLINK;
 	}
 
-	skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
+	if (test_bit(EVENT_NO_IP_ALIGN, &dev->flags))
+		skb = __netdev_alloc_skb(dev->net, size, flags);
+	else
+		skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
 	if (!skb) {
 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -79,6 +79,7 @@ struct usbnet {
 #		define EVENT_RX_KILL	10
 #		define EVENT_LINK_CHANGE	11
 #		define EVENT_SET_RX_MODE	12
+#		define EVENT_NO_IP_ALIGN	13
 };
 
 static inline struct usb_driver *driver_of(struct usb_interface *intf)
